[Cardiovascular pharmacology (XIII). The efficacy of different thrombolytic drugs in the treatment of acute myocardial infarct].

In patients with acute myocardial infarction (AMI) thrombolysis reduces the infarct area, preserves ventricular function and improves survival. This effect is more significant in men with age between 65 and 75 years, anterior ST segment elevation or branch block, during the first 6 hours of evolution. In this review the comparative studies with placebo and between different fibrinolytic agents, in different doses or in combination are reviewed, and the drug selection, the actual impact or fibrinolysis and future directions of thrombolysis in patients with AMI are discussed. Reperfusion is highest with the use of double bolus tPA of front-loaded rapid tPA infusion. Reocclusion is more frequent after tPA and minimal after urokinase or the combination of tPA and urokinase. In the GISSI-2 and ISIS-3 studies, the mortality of patients treated with streptokinase, tPA or APSAC was similar. However, in the GUSTO study, with front loaded, rapid infusion of tPA, mortality was lower than with streptokinase, although this effect was only statistically significant in patients with anterior infarction or age < 75 years. Bleeding is more common with tPA, and allergic reactions are more frequent after streptokinase and APSAC than after tPA or urokinase. Symptomatic hypotension and bradycardia are also more frequent after streptokinase or APSAC, specially in patients with right ventricular infarction. Streptokinase and APSAC generate antibodies that may neutralize the effect of a second administration even years after the first dose. On the basis of the current clinical evidence it is not possible to recommend the use of a single fibrinolytic and, due to its lowest cost, streptokinase could be considered the first choice. However, in patients with previous thrombolysis, as well as in those with right ventricular infarction, the drug of choice should be tPA or urokinase; in young patients with anterior infarction tPA is more effective and in patients with difficult controls (mobile CCU, emergency wards, etc.) APSAC or urokinase may be considered the agent of choice because their easier administration. In spite of clear evidence of the efficacy of the thrombolytic therapy, it is only used in 20%-30% of the patients with AMI, and probably there is a selection of low risk patients. For these reasons, the impact of thrombolysis in the whole population of AMI is probably lower than it could be. Future directions for the use of thrombolytic agents include a better selection of the candidates and the drug to be used as well as the early administration of thrombolytics, even before the admission to the CCU.